Guest Anonymous Posted August 1, 2003 Share Posted August 1, 2003 Hi guys, I own a 89 nissan 240sx, the previous owner swapped in a 97 ka24de twincam engine. However, the car is lacking on power, at part throttle, it seems to run okay, however at full throttle the acceleration is slow. I did all the usual maintenence, and I ordered a walbro fuel pump from florida, it arrives on monday. Since I'm waiting for the fuel pump to arrive, I thought I should check my TPS. So I went ahead and bought a BK PRECISION multimeter from FRY'S for $30. Now my TPS connector has 3 pins, one has a red wire going into it (i think power), one is white(signal), and last one is black (ground). I tested my resistance first with engine off, ignition on, i place the two probe on signal and ground, resistnace is about 1.7ohm closed, and 9.2ohm fully open, which seems to be normal. Now I go on to test teh voltage, i start the engine, let it warm up, then i disconnected the tps, then i placed the two probe on signal and ground, i set my voltage range to direct current, 2 volts. The smallest 2 range i have on my multimeter for dc is either 2volts or 200m volts. i think my tps should read .45-.55 volts at idle. So I tried setting it to 2 volts, I get nothing on the screen. Then I set it to 200m volts, I still get nothing on the screen, if i move the probes around, sometimes it will go up to .35 etc., but it's not steady at all. My question is am I doing something wrong? Or is my TPS bad? Thanks Randy Quote Link to comment Share on other sites More sharing options...
Guest jt240z Posted August 1, 2003 Share Posted August 1, 2003 You can not verify the resistance of your TPS while it is connected to the ECU. The easiest way to test your TPS is to disconnect the harness connector from the TPS. You then measure the resistance from where the black wire went to where the white wire went (At the TPS connector, not the engine harness). As you move the throttle from closed to open, you should see the resistance increase from somewhere around 1000 ohms or less (depends on TPS calibration point) to about 8000 ohms +-1000 ohms. The resistance should rise smoothly with no dead spots (no areas that jump up to very high resistances) and no negative slopes (areas where the resistance goes down instead of up). Move the throttle very slowly and keep an eye on the meter. If you're using a digital meter, you may see the meter jump momentarily while it is auto ranging. This would be normal. Once the auto ranging is complete, the value should stabilize and be slightly higher then before it auto ranged. Once the above test is completed, you can then check the resistance from where the black wire went to where the red wire went. This should read around 10,000 ohms. If the two check out, your TPS is good. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted August 1, 2003 Share Posted August 1, 2003 Hi there, thanks for the reply, my resistance is tested okay. However, i can't get any voltage reading off it, I want to see if the voltage is in spec during idle. Quote Link to comment Share on other sites More sharing options...
Guest jt240z Posted August 1, 2003 Share Posted August 1, 2003 The TPS acts as a potentiometer(variable voltage divider). The voltage source comes from the ECU into the red wire. The black wire is ground. The white wire should have a voltage that is proportionate to the amount of throttle open. The more open the throttle the higher the voltage should be. The measurement should be between the black wire and the white wire with the ECU connector attached and the ignition on. If the previous resistance checks are good, then the only TPS related problems you could have are connector corrosion, broken wire or bad ECU. Why do you suspect a bad TPS? Quote Link to comment Share on other sites More sharing options...
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